DIPYLIDIUM CANINUM 



223 



B. Tceniidcz. 



Gen. 3. Dipylidium, R. Leuck., 1863. 



Rostellum retractile with -several rings of alternating hooks, the latter 

 usually have a disc-like basis. Suckers unarmed. Genital pores prominent : 

 genitalia duplicated. Testes very numerous in the central field ; ovary 

 with two lobes ; the vitellaria, which are smaller, lie behind ; the 

 uterus forms a reticulum in the network of which the testicular vesicles 

 lie ; later on it forms into one or several sacs enclosing eggs. The eggs 

 lave a double shell. 



Dipylidium caninum (L.), 1758. 



Syn. : Tcenia canina, L., 1758, p. p ; T. moniliformis , Pallas, 1781 ; T, cucu- 

 merina, Bloch, 1782; T. elliptica, Batsch, 1786; Dipylidium cucumerinum, 

 Leuck., 1863. 



This worm measures 15 35 cm. in length and 1*5 3 mm. in 

 breadth. The scolex is small, rhomboidal, and has a club-shaped 

 rostellum on which there are three 



to four rings which carry from 

 forty-eight to sixty hooks resem- 

 bling rose-thorns, the size of the 

 foremost of which varies from O'Oii 

 - i -o < oi5, and the posterior ones 

 average O'Oo6 mm. The neck is 

 very short, the most anterior seg- 

 ments broad and short, the middle 

 as long as they are broad, the 

 mature segments are longer than 

 wide (6 7 : 2 3 mm.) fairly thick, 

 are frequently of a reddish colour, 

 and when cast off resemble cu- 

 cumber seeds. The genital pores 

 lie symmetrically at the lateral 

 borders ; the roundish ovarian fol- 

 licles arising from the reticulum 

 of the uterus contain eight to 

 fifteen eggs packed in a reddish 

 mass. The eggs are globular (0-043 

 0-050 mm.) ; the embryonal shell 

 is thin, the oncosphere measures 

 0-032 0-036 mm. 



Dipylidium caninum is a common intestinal parasite of dogs, 



FIG. 150. Dipylidium caninum. 

 (After Diamare.) On the left, the 

 scolex and the first proglottides ; on 

 the right, at the top, a packet of 

 ova ; below, hooks of the rostellum, 

 side and front views ; below, an ovum. 

 (Various enlargements.) 



